Seeing the invisible - from neutrons to photons

A world where nuclear fusion helps meet humanity's energy needs is now within reach but there is still no way of "seeing" the operation of fusion reactors in real-time, presenting critical operational and safety risks. This project will lead to a disruptive new sensor technology enabling monitoring of the operation of fusion reactors in real-time, directly addressing this urgent need.

Nuclear fusion will become a commercial proposition in the next decade revolutionising energy generation to supply abundant, clean energy. Conditions for light nuclei to fuse are extreme: hot plasma is held at 150-200 Million C by powerful magnets. This is accompanied by emission of highly energetic fast neutrons with 14.1 MeV energy. Materials adjacent to fusion reactions must tolerate very high temperatures and damaging neutrons so developing sensors and sensor materials capable of measurements in such conditions are among the greatest challenges.

This project will directly address these urgent drivers by delivering an entirely new class of durable inorganic glass scintillators, which convert neutrons to detected photons. These will be capable, for the first time, of detecting fast 14.1MeV neutrons emitted from fusion reactions at high temperatures, enabling real-time insight into operation of fusion reactors, far advanced from current state-of-art. This is timely as UK fusion transitions from lab- to pilot- to commercial-scale (e.g. STEP) as the need for real-time, robust sensors capable of years of operation is urgent.

Measurement methods for neutron flux in high intensity areas are few and new approaches are needed for next generation tokamaks. Fission chambers and gas filled detectors are fragile and surveillance foils do not provide real-time information. No technology yet exists capable of doing what we are attempting. Our novel sensors will enable a step-change by providing operators real-time measurements in extreme environments, accelerating design processes and enabling more efficient and advanced control mechanisms, greatly enhancing safety. Inorganic glasses can be produced at scale and are tolerant to damaging neutron radiation and high temperatures. However, current inorganic glass sensors cannot reliably detect fast 14.1 MeV neutrons from nuclear fusion as there is little scintillation. Plastic and liquid scintillators (including organic glasses) are sensitive but have very low tolerances to high temperatures and radiation damage. Developmental diamond-based sensors are small (< 5 cm) and cannot be produced at scale.

Our new inorganic glasses capable of detecting fast neutrons will bring game-changing advances in neutron detection for fusion energy. The most exciting potential rewards of this high-risk project will be acceleration and enhancement of development, design, construction, and operational safety of commercial nuclear fusion power plants to be built in the UK and globally in the next decade.